About Add Audio
Replace or layer a new audio track onto your video. Background music, a voiceover, sound effects, or a complete dub.
How add audio works
Add Audio is two operations in one: replace (the new track takes over completely, original audio is muted) and mix (both tracks play together at the levels you set). The mix engine handles loudness so your music doesn’t drown out the dialogue. You can either set fixed levels or use auto-ducking, which lowers the music whenever speech is detected.
NextConvert handles every combination of input formats: MP3 music onto an MP4 video, WAV voiceover onto a MOV, OGG sound effect onto a WebM. The output audio is encoded to match the chosen container so playback is universal.
Common workflows: adding background music to a vlog, putting a narration over a screen recording, dubbing a tutorial in a second language, or stamping a sound effect onto a comedy edit.
When to use it
Background music
Add royalty-free music under a vlog, a wedding video, or a product demo.
Voiceover narration
Lay narration over a screen recording, a slideshow, or B-roll footage.
Dubbing
Replace original audio with a translated voice track for international distribution.
Sound effects
Drop in whooshes, stings, and reactions for edited content.
Supported formats
Input
Output
Step-by-step guide
- 1
Upload video and audio
Drop both files. The audio waveform appears so you can see exactly where it lands relative to the video.
- 2
Choose replace or mix
For mix mode, set the relative volume of original and new audio. Enable auto-ducking if you want music to quiet down during dialogue.
- 3
Combine and download
We mux the new audio into the video and stream the result back.
Tips for the best result
- If the music is longer than the video, it will be cut at the end. Use Trim first to match exactly, or enable loop mode.
- For voiceover, record at a higher level than you think you need. Quieter sources lose intelligibility once dialled into the mix.
- Pick royalty-free music (YouTube Audio Library, Free Music Archive) to avoid copyright strikes on social platforms.
Privacy and security
Files are uploaded to our processing servers over an encrypted connection and removed automatically after the job completes (usually within a few hours). We never share your media or train models on it. You can also delete a job manually at any time from your dashboard.
Read our full privacy policy for retention timelines and our list of subprocessors.